The water adduct of propentdyopent, which have two propionic acid groups and two methyl groups on two pyrrole rings and a hydroxyl group at the valley position, was prepared by the oxidation of hemin with hydrogen peroxide. Esterification of the two propionic acid groups and substitution of alkoxy group for the hydroxy group were studied to examine the reactivity of the adduct. The esterification took place with the substitution of methoxy group on treatment with a solution of 2% sulfuric acid in methanol at 60℃. The substitutions of methoxy and ethoxy groups were attained without any esterification on treatment with a solution 10% acetic in methanol at 80℃ and a solution of 10% acetic acid in ethanol, respectively. Only esterification was performed on treatment with an ethereal solution of diazomethane. Hydrolysis of the ester occurred simultaneously with the substitution of hydroxyl group for methoxy group on standing with 0.5N hydrochloric acid at room temperature. Those compounds were purified by thin-layer chromatography and identified with mass and nmr spectra.